This invention is directed primarily to providing an improved retractable vertical restraint mechanism for use in an aircraft cargo handling and/or aerial delivery system. As is known, cargo drops by parachute from aircraft have been employed extensively in military operations and disaster relief situations. In the usual parachute cargo delivery system, loaded airdrop platforms are guided for movement along the longitudinal axis of the aircraft between parallel guidance and restraint rails secured to the aircraft floor. A continuous vertical restraint lip is incorporated into each of these rails. The platforms can be pulled backwardly out of a rear cargo receiving and delivery opening by means of a parachute during airdrop operations. Similarly, loaded pallets can be guided between the rails and pushed out of the opening and down a ramp onto the ground as the airplane taxis on a runway during combat off-load operations.
For that portion of the rails immediately forward of a hinged cargo ramp, the vertical restraint lips incorporated into the rails must be retractable to permit loading and unloading of cargo pallets and airdrop platforms when the cargo ramp is sloped. The retractable vertical restraint lips must be locked in the horizontally-extended restraint position to provide the necessary vertical restraint of the pallets and airdrop platforms during flight. Deliberate action must be required to unlock the retractable vertical restraint lips from the restraint position to avoid possible inadvertent unlocking by, for example, personnel unintentionally bumping a latch control with their feet. During airdrop of cargo, each retractable vertical restraint lip must be positively locked in the restraint position to prevent the airdrop platform from lifting out from between the restraint rails due to turbulence. Moreover, each retractable vertical restraint lip must provide a continuous and smooth lower surface without notches or edges that might obstruct the necessary movement of the platform should a platform lift during parachute extraction.
The vertical restraint lips must be movable into a retracted, non-restraining position to permit unloading of cargo down the inclined ramp during combat off-load operations. In this instance, inadvertent movement of a vertical restraint lip into a locked restraint position cannot be tolerated. Therefore, deliberate action must be required to move each vertical restraint lip from the retracted position into the restraint position. In view of the foregoing, a positive and readily visible indicator is necessary to inform personnel when a retractable vertical restraint lip is not latched in the retracted position.
It is desirable for each retractable vertical restraint lip to be foot operated and accessible for operation with or without pallets and/or airdrop platforms present between the restraint rails. When the retractable vertical restraint lips are in the restraint position, the top surfaces of the restraint rails should be continuous and smooth, without large notches or edges, to accommodate sliding of the foot on a force-transfer device during parachute extraction of the cargo.
The guidance and restraint rails in the cargo compartment may fold inboard for stowage. In such a case, hinged covers supported by the stowed rails may be used to provide a smooth, flat void-free floor in the cargo compartment. Therefore, the outboard face of the restraint rails with the retractable vertical restraint lips in the cargo-restraining position and/or the retracted position should provide a flush surface for stowage.